铝合金阳极氧化膜层结构对粘接性能的影响

Effect of Aluminum Alloy Anodic Oxidation Film Structure on the Adhesive Property

目的研究铝合金阳极氧化膜层厚度与孔径对粘接性能的影响。方法制备铝合金阳极氧化膜层,配制电解液成分为120 g/L H_2SO_4,60 g/L H3PO4,7 g/L CH_3COOH,温度为22℃。通过改变阳极氧化时间和阳极氧化电压,制备膜层厚度不同和孔径尺寸不同的阳极氧化膜层结构,对阳极氧化膜试样涂TS-805胶粘剂,加压固化。通过拉伸剪切强度测试和湿热环境耐久性能测试,评价氧化膜层厚度和孔径对阳极氧化膜粘接性能的影响关系。结果随着膜层厚度的增加,拉剪强度逐渐升高,达到一定厚度后,膜的拉剪强度不再增加反而降低,当膜层厚度为9.41μm时,铝合金粘接件的拉剪强度最高为25.06 MPa。在膜层厚度一定的情况下,氧化膜层结构中孔径尺寸对拉剪强度的影响较小;氧化膜层的湿热环境耐久性能随着氧化时间的增加而提升,当氧化时间为30 min时,膜层湿热耐久性能最优;膜层湿热环境的耐久性能受膜层孔径尺寸的影响较小。结论铝合金阳极氧化膜层结构中多孔层的孔深对粘接接头的粘接强度有影响,膜层过厚在粘接过程中粘接界面易形成气孔而降低粘接的拉剪强度,膜层厚度的最佳值与选用胶粘剂的黏度和多孔层的孔径有关,孔径对粘接拉剪强度的影响不明显。铝合金粘接的湿热耐久性能与氧化膜的孔径关系较大,对同一氧化体系的氧化膜层结构,孔径越大,湿热耐久性能越高。氧化电压是控制氧化膜层结构的主要因素,可以通过控制氧化电压提高氧化膜层粘接的湿热耐久性能。

Objective To study the effect of the thickness and pore size of the aluminum alloy anodic oxidation film on the adhesive property. Methods Aluminum alloy anodic oxidation film was prepared. Electrolyte with 120 g/L H2SO4, 60 g/L H3PO4 and 7 g/L CH3COOH was prepared at temperature of 22℃. Anodized layer structures with different film thickness and different pore size were prepared by changing the anodic oxidation time and the method of anodic oxidation voltage. TS-805 adhesive coating was sprayed on anodic oxide film and then pressurized for solidification. Effects of thickness and pore size of oxide film layer on the adhesive property of anodic oxide film were evaluated by tensile shear strength test and hot and humid environment endurance test. Results Tensile shear strength increased with the increase of membrane thickness. At a certain thickness, it would not increase but decrease. When the membrane layer thickness was 9.41 gm, the tensile shear strength was up to 25.06 MPa. When the film thickness was up to a certain value, pore size influenced the tensile shear strength less. Hot and humid environment durability would be improved with the increase of oxidation time. When the oxidation time was 30 min, the hot and humid environment durability was best. It was less affected by the pore size. Conclusion Hole depth of porous layer in anodic oxidation film has an effect on bonding strength of the adhesive-bonded joint. Too thick membrane layer may cause pores on the adhesive bonding interface in the bonding process and further reduce the tensile shear strength of adhesive layer. The optimal thickness is related to the viscosity of selected adhesive layer and the pore of porous layer. Pore size has unapparent effect on the bonding shear strength. Hot and humid environment durability of the aluminum alloy is greatly related to the pore size of oxide film. For the oxide film layer structure of the same oxidation system, the larger the pore size is, the higher the hot and humid environment durability is. Oxidation voltage is the main factor to control oxide film layer structure. It can improve the hot and humid environment durability of oxide film layer by controlling the oxidation voltage.